The present invention relates to a sensor array, particularly for vehicle air conditioners.
Modern vehicle air conditioners, which are operated by use of the R134a refrigerant, normally have a pressure sensor on the “high-pressure side” behind the compressor, for monitoring the operating pressure and for controlling an electric fan stage. When the operating pressure exceeds a defined maximal pressure, a control will intervene, which controls the operating pressure down into a “normal pressure range”, for example, by switching off the compressor.
For various reasons, carbon-dioxide-operated vehicle air conditioners will probably become significant for future vehicle generations. For controlling a “CO2 refrigeration cycle”, the refrigerant pressure and, in addition, the refrigerant temperature behind the compressor, are required as signal parameters. In the case of “CO2 air conditioners”, the refrigerant pressure and the refrigerant temperature behind the compressor are mutually independent physical parameters. For monitoring the refrigerant pressure and the refrigerant temperature, a pressure sensor and, in addition, a temperature sensor, may be provided. which are each coupled by separate electric lines or by a bus system to an electronic unit of the air conditioner. By way of the pressure sensor and the temperature sensor, the refrigerant pressure and the refrigerant temperature can be measured, can be transmitted to the electronic unit, and can be processed there. The electronic unit triggers one or more “control elements” of the refrigeration cycle.
The use of two separate sensors, which are each coupled by way of separate electric lines with the electronic control unit, and the “central processing” of two signals in the electronic unit, require high wiring and computing expenditures. It is also disadvantageous that, in the case of such arrays, the temperature sensor and the pressure sensor are each accommodated in a separate housing, and are each separately connected to the fluid cycle of the air conditioner, which may result in leakage problems.
In one aspect of the invention, a compact and cost-effective sensor array is created for monitoring at least two physical parameters, particularly for monitoring a refrigerant pressure and a refrigerant temperature in a vehicle air conditioner.
A sensor array, particularly for vehicle air conditioners, is provided, in which a first sensor element is provided for measuring a first physical parameter, and a second sensor element is provided for measuring a second physical parameter. The first physical parameter may be a refrigerant pressure, and the second physical parameter may be a refrigerant temperature. The two sensor elements are accommodated in a common housing which can be connected directly to the fluid cycle of a vehicle air conditioner. Thus, only a single “connection point” to the fluid cycle is required for the two sensor elements, which minimizes the danger of leakages. In comparison to separate sensor elements, this also reduces the weight and the number of individual components. It is also important that the sensor array is an “intelligent sensor array”. In this context, “intelligent” means that the two sensor elements are connected to an electronic unit which is arranged in the, or directly on, the housing of the sensor array, which electronic unit carries out an “analysis” or “preprocessing” of the sensor signals and switches an “analyzed” signal to a signal output of the sensor array. The signal output is connected by way of an electric line or by way of a bus system with an electronic control unit of the vehicle air conditioner arranged separately from the sensor array.
An “analyzing module” is integrated in the electronic unit, or is stored there as software. As a function of measured “momentary values” of the physical parameters, according to a defined selection logic, the analyzing module determines one of the two measured physical parameters as a “momentarily relevant parameter” and switches an electric sensor output signal corresponding to the momentarily relevant physical parameter to the signal output of the sensor array. Or, on the basis of the “momentarily relevant parameter”, the analyzing module forms an electric sensor output signal and switches the latter to the signal output of the sensor array.
By way of a sensor array according to the invention, two physical parameters may therefore be “monitored” simultaneously. The “electronic sensor unit”, to which the two sensor elements are connected, selects, as a function of the momentary measured values and a given selection logic, the measuring signal to be momentarily considered as “relevant” or to be momentarily considered as “critical”, and switches a sensor signal formed on the basis of the momentarily relevant or critical signal to the sensor signal output. In comparison to conventional systems, in which two sensors are each separately wired with the central electronic control unit of the vehicle air conditioner, the wiring expenditures are cut in half with the present invention. In addition, the data quantity to be processed in the central control unit of the vehicle air conditioner is reduced because the electronic sensor unit “on the input side” “transmits” only the momentarily relevant measuring signal to the electronic control unit of the vehicle air conditioner, or only an electric sensor signal formed on the basis of the momentarily relevant measuring signal is transmitted to the central electronic control unit.
As mentioned above, the sensor array may be a combined pressure/temperature sensor array. The housing of the combined pressure/temperature sensor array contains a pressure sensor and a temperature sensor, as well as the electronic sensor unit for analyzing the sensor signals and for “conditioning” the output signal. The electric output signal of the sensor basically represents a pressure signal which, as required, contains certain information of a temperature signal by a corresponding conversion into an “equivalent pressure signal”, which will be explained in greater detail in the following.
It is explicitly pointed out that the invention is not limited to a sensor array having two sensor elements. The sensor array may also have more than two sensor elements, which each measure a physical parameter. The analyzing module would then determine the momentarily relevant parameter from the more than two physical parameters according to a corresponding selection logic and form the sensor output signal on the basis of the momentarily relevant parameter.
Advantageous embodiments and further developments of the invention are described and claimed herein.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.